Field of the Invention
Exemplary embodiments of the present invention relate to an electronic parking brake system for a vehicle, and more particularly, to an electronic parking brake system for a vehicle and a method of driving the system, which are capable of stopping the vehicle when the operation of a vehicle service brake is impossible during the travel of the vehicle.
Description of the Related Art
An electronic parking brake system that improves a wire type parking brake system has been employed. The electronic parking brake system determines the speed of a vehicle, the rotation of an engine, and the operation of a brake by an electronic control unit (ECU) when the vehicle stops, thus causing the brake to be driven. Thus, even if a driver does not apply the brake while the vehicle stops, there is no possibility that the brake is released. Meanwhile, when the vehicle starts to run, the brake is automatically released from a locked state merely by pressing on an accelerator pedal. Thereby, even when the vehicle starts on a slope, the vehicle is not pushed backwards. Further, even when there is a severe traffic jam, the vehicle moves forwards only when a driver increases the speed. Consequently, it is unnecessary for the driver to frequently press on the accelerator pedal. During the travel of the vehicle, the ECU detects the vehicle speed and recognizes that the vehicle is moving, so that the electronic parking brake system does not work while the vehicle is running. However, the electronic parking brake should have the function of stopping the vehicle that is running, in the event that the operation of the service brake is impossible. Such a conventional electronic parking brake system is problematic in that a control value is tuned by repetitive experiments, so that a lot of time and money is required to tune the control value.